[libvirt] image locking?

Daniel P. Berrange berrange at redhat.com
Wed Oct 15 20:59:12 UTC 2008

On Wed, Oct 15, 2008 at 01:47:36PM -0700, Itamar Heim wrote:
> The main issue is indeed across nodes. As you pointed out, fnctl() won't
> solve the issue for iSCSI.
> What about the leased lock mechanism, for example, with libvirt playing
> an external watchdog and terminating the qemu process if it cannot renew
> the lock, or a central (nfs? Central service) storage to maintain the
> global locks.

When you get to that level of cleverness, it seems to me that it is verging 
on a complete re-implementation of DLM (distributed lock manager), which 
really, AFAIK, needs a proper cluster setup so it can safely fence 
mis-behaving nodes, and avoid quorum/split-brain problems.

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